City children are more likely to have food allergies than kids who grow up in rural areas, according to a new study published last month in the Journal of Clinical Pediatrics. A team of researchers from Illinois and Missouri surveyed parents of almost 40,000 children nationwide, finding that about 8 percent of children have allergies, but that that number varies depending on location. The more remote an area is, the less likely children there are to develop food allergies. According to the study, 9.8 percent of children in urban centers have food allergies, while only 7.6 percent of children in suburbs are allergic to a food. In rural areas that number drops to 6.2 percent. Interestingly, peanut allergy was the most common type of food allergy in 5 of the 6 geographic areas (urban center, metro city, urban outskirts, suburban areas and small towns), but in the most remote category – rural areas – milk beat out peanuts by a small margin. Ruchi Gupta, the study’s lead researcher, says the team is not sure why this trend occurs. “I thought it was interesting,” she told Food Safety News, but she says more studies are needed to answer the whys behind this and other findings in the study. “This is what research always does,” says Gupta, an Assistant Professor of Pediatrics at Northwestern University and researcher at Children’s Memorial Hospital in Chicago. “You figure out one thing and you open up a lot of questions.” Another question-generating discovery in the study is that kids in sunnier states are more likely to have food allergies than those in cloudier regions. Gupta says this pattern is at odds with findings from other food allergy studies, which have shown that food allergies are more common in the North, and have led researchers to believe that food reactions could be related to a lack of Vitamin D. “I don’t think we can totally refute the Vitamin D theory,” says Gupta, noting that more research is needed, “but the trend that we saw was higher prevalence in the South compared to the North.” While studies on food allergy prevalence are relatively uncommon, and this is the first to rely on parent reporting rather than healthcare records, research on other types of allergies has turned up similar results: children in urban areas seem to suffer more from allergies than those in rural settings. One popular explanation for this phenomenon is the “hygiene hypothesis,” which suggests that because children in urban homes live in more sterile environments, they are not exposed to as many pathogens, so their immune systems start fighting things they shouldn’t be fighting – such as foods. Another possible explanation is that children raised in rural areas may be introduced to a larger variety of foods at an earlier age, thus reducing the likelihood they’ll develop a food allergy. “People really want to know what is it in the environment [that affects food allergies] and I think that’s the next big research question,” says Gupta. “We really need to spend some time and energy figuring out what these potential triggers to food allergy are in urban environments.” The way to figure this out, she says, is to track what a child is exposed to from pregnancy until adulthood in order to figure out which factors are associated with higher food allergy rates. There’s also one explanation for the study’s findings that would mean environment may not play a role in food allergies after all. What if kids in rural areas simply don’t see a doctor as often and so their allergies are less likely to be detected? “One of our big questions is: is this real or are kids not getting diagnosed?” explains Gupta. “Are kids going to the doctor more in urban areas and have more chance of getting diagnosed with food allergies?” Indeed the study found that a child with a food allergy living in a big city was just as likely to have a life-threatening reaction as a child in a small town. Is it possible that allergies are just as common in both places but children in rural areas are less likely to be diagnosed before they have a life-threatening reaction? It’s possible, says Gupta. But it’s unlikely, since parents were doing the reporting for this study, not doctors. “Even if these children were not diagnosed by a physician but they did seem to have a convincing food allergy based on the symptoms that the parents told us and the types of foods that the kids were allergic, to we did count them as a food allergy.” Regardless of whether diagnosis rates affect allergy rates, Gupta says, the fact that allergy severity doesn’t depend on region is a reminder to all parents of kids with food allergies to take proper precautions. “This is really important to note,” says Gupta. “There may be less food allergies in rural areas, but if you do have a food allergy, you still have an equal chance of having a severe, potentially life-threatening reaction.” “Just because a child typically has a mild reaction to a food when they eat it doesn’t mean that a given day they couldn’t have a severe reaction,” she warns. “We don’t know. If they’ve had a mild reaction in the past, the next time the reaction could become more severe.” Parents should always report a child’s food allergy to his or her doctor, Gupta says, so that the child can be prescribed medication to prevent a life-threatening reaction.